Many parts of the world lack sufficient rainfall at different times of the year to maintain the health of turf and landscaping. Irrigation systems are therefore used to deliver water to such vegetation from municipal water supplies and wells according to a watering schedule. A typical irrigation system comprises a programmable controller that turns valves ON and OFF to deliver water through a plurality of sprinklers connected to the valves via subterranean pipes. These sprinklers are usually rotor-type, impact, spray, or rotary-stream sprinklers. A rotor-type sprinkler includes a—riser that houses a turbine and gear reduction mechanism that rotates a nozzle that typically ejects a relatively large stream of water. The riser may be installed above the ground or be installed within an outer housing that allows it to pop-up when water pressure is applied.
Unfortunately rotor-type sprinklers often apply water at an application rate that is greater the ability of the soil to absorb it. When water is applied at a higher application rate that the soil can absorb, the excess water runs off of the irrigated area and is wasted. In applications where sprinklers are used to irrigate landscape that cannot absorb water very fast, or on hills and slopes, it is desirable to use low precipitation rate sprinklers. Low precipitation rate rotary-stream sprinklers have been installed in residential and commercial applications. However, rotary-stream sprinklers have a limited range or radius and are not suitable for use when large areas of landscape must be covered.
U.S. Pat. No. 4,836,450 of Hunter discloses a low precipitation rate rotor-type sprinkler utilizing a diffuser device that selectively interrupts the stream of water emitted from the nozzle and operates only in a part circle (oscillating) mode. The stream interrupter only interrupts the stream of water during counter-clockwise rotation of the nozzle and does not interrupt the stream during clockwise rotation of the nozzle. U.S. Pat. No. 4,836,449 of Hunter discloses a rotor-type sprinkler utilizing a diffuser device that selectively interrupts the stream of water emitted from the nozzle and operates only in a full circle (360 degree) mode. U.S. Pat. No. 5,423,486 of Hunter discloses a rotor-type sprinkler that operates only in a full circle (360 degree) mode with a stainless steel sleeve added to protect the intricate workings of the diffuser mechanism of the sprinkler from contamination of the surrounding soil when it is extending or retracting during normal operation.